Most trailer carried spraying systems use separate independently driven electrical or mechanical pumps which are carried by the trailer. Such spraying systems are shown for example in the following U.S. Pat. No. 2,757,044 (Gerbracht), U.S. Pat. No. 2,975,940 (Nybakke), and U.S. Pat. No. 7,124,961 (Wilting).
It has been proposed to use the power from the tractor or other tow body to drive the pump for the sprayer system, and self pumping spraying systems using peristaltic pumps connected to the trailer drive wheels have been proposed. See the following U.S. Pat. No. 2,703,256 (Mascaro), U.S. Pat. No. 3,534,533 (Luoma), U.S. Pat. No. 3,807,605 (Meharry et al.), U.S. Pat. No. 4,240,583 (Hughes), U.S. Pat. No. 4,296,875 (Borglum), U.S. Pat. No. 4,483,486 (Magda), U.S. Pat. No. 4,473,188 (Ballu), U.S. Pat. No. 5,109,791 (Matsumoto et al.) and U.S. Pat. No. 5,333,795 (Jessen). Such peristaltic pump equipped sprayers have not achieved commercial acceptance. It is believed this is because the spray is pumped in widely spaced pulses, rather than in a generally steady flow of liquid, as have been provided by separate electrical and mechanically driven pumps.